Brake



p 6, 2- w. H. DELAHAYE- 1,876,136

BRAKE Filed May 1, 1929 I INVENTOIZ WALTER HAMILTON DELAHAVE.

5 ATTORNEY Patented Sept. 6, 1932 UNITED STATES PATENT OFFICE, I

WALTER HAMILTON DELAHAYE, OF OTTAWA, ONTARIO, CANADA, ASSIGNOB TO BEN- DIX BRAKE COMPANY, OF SOUTH BEND, INDIANA BRAKE Application filed May 1, 1929. Serial No. 359,446.

This invention relates to an improved type Y ofv brake, and particularly those adapted for an automobile, which have the shoes so arranged that movement of one shoe causes the remaining shoes to be applied with an increased pressure. Such brakes are termed Servo or self-energizing brakes and it is the object of the invention to provide an improved construction of such Servo brakes.

One of the objects is to provide a brake which is fully effective when the wheel is at rest and a secondary object is to provide for a Servo action for both direct-ions of rotation of the wheel. Another advantage in the construction about to be disclosed is that the trailing shoe is applied with greater force than the reversely acting shoe which lessens the tendency of the latter shoe to grate when applied.

The construction of the brake will now be described with reference to the accompanying drawing in which Figure 1 is an elevation of the preferred form of brake, the shoes being shown applied, g

but in the position occupied prior to any Servo action;

Figure 2 shows a modified form of Servo shoe; and

Figure 8 is a section on line 3-3 of Figure 2.

In the drawing all return springs and stops have been omitted but it is obvious that such must be used. Their construction, however, may vary and it is well within the capabilitise of any skilled mechanic to construct these. The gist of the invent-ion lies in the means for applying the force created by the Servo shoe to the main shoe.

Reference numeral indicates a brake drum and 2 the customary flange on the axle which is indicated at 3. The brake consists of two similar shoes 4: mounted on fixed pivots 4 and a secondary shoe 5. This shoe 5 is the Servo shoe and it is so mounted that it has certain amountsof movement in both directions between the pivots 4c. The shoes I areof the construction usually employed in internal expanding cam brakes, but a novel means for operating these from the Servo shoe 13 provided, and they are necessarily shorter than usual to provide space for the Servo shoe.

Instead of the customary cam the shoes 4:

have between them the end of a lever 6 which any type of sliding joint may be provided.

T he end of the tubular socket is provided with a bearing surface 12 adapted to contact with a cam 13 which is mounted on a rock shaft 14: ournalled in the lever 6. This rock shaft passes freely through an arcuate slot 15 in the flange 2 and is provided with the customary short lever 16 of the regular brake riging.

It is, of course, understood that all the shoes carry the customary brake lining 117 and While they are shown of the rigid I -section type this is not necessary and ahy other type may be used.

The operation of the device although selfevident will now be briefly set forth. When the operating lever 16 causes rotation of the rock shaft 14, the cam 13 engages the surfaces 12 and forces the Servo shoe 5 against the brake drum 1. However, as the lever 6 is floating the reaction of the cam also forces the lever in the opposite direction so that the collar 9 engages the ends of the brake shoes 4 v ing movement. As this latter movement is in proportion to the speed of rotation of the drum 1 it will be understood that as the speed lessens the brake pressure is decreased. Such operationdecreases the tendency of the wheels to lock which at times is very dangerous.

Referring to Figure 2, a modified form of Servo shoe is shown. Instead of a Servo shoe 5 slidably mounted on the lever 6 the latter carries two Servo shoes 5 pivoted at 17 on the lever. These shoes present a drum-engaging surface 18 and also two cam engaging surfaces 19 lying on opposite sides of the cam. Instead of the single lobed cam 13 a double lobed cam 20 is employed. The operation of the device is similar to the form described above and therefore repetition is deemed unnecessary.

The above sets forth examples embodying applicants invention, but various, changes may be made without departing from the spirit of the invention. It will be seen that as the lever swings the pressure of the collar 9 will increase on the end of the trailing shoe, but will be lessened on the reversely acting shoe, the advantage of which has-been pre viously explained.

It is the intention of the applicant to cover the invention broadly including such modifications as may come under the scope of the appended claims.

What I claim is:

1. In a Servo brake, a fixed support, a main shoe, a lever operating said main shoe, a Servo brake shoe slidable on said lever and means supported on said lever to cause outward movement of said shoe to engage a brake drum.

2. In a brake as claimed in claim 1, said Servo operating means consisting of a cam ournalled in said lever, said journal extendin g outwardly through an arcuate slot in said support and being provided with an operating lever.

3. In a brake and in combination with a fixed support, a pair of anchored shoes extending over a major portion of the periphery of the brake, the adjacent ends of said shoes being free, a Servo shoe occupying the minor portion of the periphery of the brake and means for simultaneously urging the Servo shoe and the free ends of the anchored shoes radially outwards.

4. In a device as claimed in claim 3, said means being adapted on engagement of the Servo shoe to also apply a circumferential expanding force to the free ends of the anchored shoes.

5. In a device as claimed in claim 3, said means consisting of a lever slidably engaged said stop to engage the free ends of the shoe.

7. In a Servo brake and in combination with a support, a pair of oppositely extending anchored shoes and a Servo shoe lying between said anchors, the free ends of the anchored shoes presenting opposed bearing surfaces lying in a radial plane, a diametrically disposed floating lever between said free ends, the Servo shoe being slidably mounted on the other end of said lever, said- Servo shoe having a socket formed therein to provide said slidable mounting, said socket presenting a cam-engaging portion to cooperate with an operating cam carried by said lever.

8. In a brake, a support, a pair of shoes anchored on said support, the free ends of said shoes presenting opposed bearing surfaces, a brake drum cooperating with said shoes. a lever between said surfaces extending diametrically of the drum to the opposite side thereof, a Servo shoe, and means for causing said Servo shoe to engage the brake drum, said Servo shoe causing movement of the lever upon engagement with the drum during the braking operation, and said lever having a radial thrust transmitting portion engageable with the free ends of said pair of shoes.

9. In a brake, a support, a pair of shoes anchored on said suport, the free ends of said shoes presenting opposed bearing surfaces, a brake drum cooperating with said shoes, a lever between said surfaces extending diametrically of the drum to the opposite side thereof, a Servo shoe, and means carried by said lever for creating a thrust upon the Servo shoe to cause it to engage the brake drum, said Servo shoe causing movement of said lever upon engagement with the drum during the braking operation.

In testimony whereof I have afiixed my signature.

WALTER HAMILTON DELAHAYE. 

